JDK-8236733](https://bugs.openjdk.java.net/browse/JDK-8236733).
Bump the release version to 15. As noted in the JBS issue, I will wait until right after the `jfx14` fork to integrate this. ------------- Commits: - 50f38ab6: 8236733: Change JavaFX release version to 15 Changes: https://git.openjdk.java.net/jfx/pull/83/files Webrev: https://webrevs.openjdk.java.net/jfx/83/webrev.00 Issue: https://bugs.openjdk.java.net/browse/JDK-8236733 Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod Patch: https://git.openjdk.java.net/jfx/pull/83.diff Fetch: git fetch https://git.openjdk.java.net/jfx pull/83/head:pull/83 PR: https://git.openjdk.java.net/jfx/pull/83
